Esters of 2-cyclohexene-1-caproic acid



Patented Dec. 13, 1949 Gerald H. Colemanj Freeland, Michi, assigno'r'tm The;l)ow-:-Chemic al Company, Midland, Mich nw em iDel a .7 pa n 1 The present invention is related to a novel group of ester compounds and is particularly concerned with esters of 2-cyclohexene-1-caproic acid having the formula CH CH r on: oncra)l-oo -;a

CHr-C 2 I F wherein R. represents anaalkylcyclohexyl,cyclohexylcyclohexyl or phenylcyclohexyl-"-radical:' These new esters are mostlyvwaterwhite liquids, insoluble in water and solublein-many organicsolvent's. ".They *are valuable as intermediates for the preparation of more complex organic derivatives, as modifiers in plastic compositions, and as parasiticide toxicants.

The new compounds are prepared by reacting the methyl ester of 2-cyclohexene l' caproic acid with an alkylcyclohexanol, cyclohexylcyclohexanolor 'phenylcyclohexanol, preferably in the presence of a smallamount of aluminum ethoxide or powdered iron as catalyst. Substantially equimolecular proportions of the;methyl---2-cyclohexene-l-caproate and substituted cyclohexanol have been found to give the desired esters in good yield. The reaction is carried out at the boiling temperature of the reaction mixture and under reflux. When the reaction is complete, the crude mixture is fractionally distilled under reduced pressure to obtain the desired ester product in substantially pure form.

The methyl 2 cyclohexene i caproate, employed as a starting material, may be prepared by reacting 2-cyclohexene-1-caproic acid with a large molecular excess of methyl alcohol. The reaction is carried out at the boiling temperature of the reaction mixture and under reflux. When the reaction is complete, the crude mixture is fractionally distilled to obtain the methyl 2- cycloheXene-l-caproate. This product boils at 103 C. at 2 millimeters pressure and has a specific gravity of 0.958 at /4 C.

2-cyclohexene-1-caproic acid may be prepared by the oxidation of cyclohexanol. In a representative preparation, 5 moles of anhydrous sodium hydroxide, 5 moles of anhydrous potassium hydroxide, and 0.43 mole of caproic acid were mixed and heated to fusion. The fused mixture was stirred continuously and. maintained at about 300 C. while 13.28 moles of cyclohexanol was added portionwise thereto. The mixture was then cooled, dissolved in water, and steam distilled to remove traces of cyclohexanol and low boiling by-products. The residual aqueous layer was evaporated to about 3 liters volume and Serial No. 69 ,989 q l U 'Clanns. (Cl. 260-468) acidified with hydrochloric acid -to liberate"the organic acid reactionproducts as a water-1m miscible layer. This layer was separated and fractionally distilled under vacuum whereby there was obtained 4.113 moles;..of-;,2:-Cyclohexene-1- caproic acid. This compound boils at -198 C. at 38' millimeters pressure andhas a specific gravityof 0.9861 .at'20/4- C;

The following examples illustratethe invention but are not to be construed as limiting the same.

Example 1.,The z-cyclohearylcyclohexyl ester of Z-ciyclolzemene-I -caproic acid 42 grains (0.2 mole) of methyl 2-cyclohexenel-caproate, 36.4 grams (0.2 mole) of "2=cyclohexylcyclohexanolj and- .0.1 gram of aluminum ethoxide were mixed together and heated for 10 hours at a temperature of from 200 to 250 C. and under reflux. The crude product was then fractionally distilled under reduced pressure to obtain the 2-cyclohexylcyclohexyl ester of 2- cyclohexene-l-caproic acid as a water-white liquid boiling at 275 C. at 18 millimeters pressure and having a specific gravity of 0.980 at 25/25 C. This compound was soluble in petroleum distillate and carbon tetrachloride and insoluble in water.

Example 2.-The 4-cyclohexylcyclohexyl ester of Z-cyclohexene-Z -ca.proz'c acid in water and 95 per cent ethanol and soluble in carbon tetrachloride and petroleum distillate.

Example 3.4-methylcyclohexyl ester of Z-cyclohexane-1 -caproic acid CH=CH CH2OH2 o 2 cH(oH2) t-oo3 CH-CH3 CHg-C z \CHFCHI 42 grams (0.2 mole) of methyl 2-cyclohexenel-caproate, 22.8 grams (0.2 mole) of 4-methylcyclohexanol and 3 grams of powdered iron were mixed together and heated at 200 tov 225 C. for 12 hours and under reflux. The crude product was filtered and the filtrate fractionally distilled under reduced pressure to obtain the 4-methylcyclohexyl ester of 2-cyclohexene-l-caproic acid as a water-white liquid'boiling at 205 to 215 C. at millimeters pressure and having a specific gravity of 0.958 at /25 C. This product was soluble in petroleum distillate, carbon tetrachloride and 95 per cent ethanol, and insoluble in water.

Emample 4.-2-phenylcyclohe:cyl ester of Z-cyclohewene-I-caproic acid In a manner similar to that of Example 1, 42 grams (0.2 mole) of methyl 2-cycl0heXene-1- caproate, 35.2 grams (0.2 mole) of 2-phenylcycloheXanol and 0.5 gram of aluminum ethoxide were heated together at 260 to 270 C. for 8 hours. Upon fractional distillation of the crude reaction product, there was obtained the 2-phenylcycloheXyl ester of 2-cyclohexene-l-caproic acid as a water-White liquid boiling at 223 to 225 C. at 3 millimeters pressure and having a specific gravity of 1.014 at 25/25 C. This product was in- 4 soluble in water and soluble in carbon tetrachloride and petroleum distillate.

In a similar manner, other esters of 2-cyclohexene-l-caproic acid may be prepared of which the following are representative.

The 2-methylcyclohexyl ester of Z-cyclohexene-l-caproic acid by heating methyl 2-cyclohexene 1 caproate and 2 methylcyclohexanol with aluminum ethoxide.

The 2,4-dimethylcyclohexyl ester of 2-cyclohexene-l-caproic acid by heating methyl 2-cyclohexene-l-caproate and 2,4-dimethylcyclohexanol with aluminum ethoxide.

The 4-tertiary butylcyclohexyl ester of 2-cyclohexene-l-caproic acid by heating methyl 2-cyclohexene-l-caproate and 4-tertiary butylcyclohexanol with aluminum ethoxide.

I claim:

1. An ester having the formula CH=CH o wherein R represents a member of the group consisting of the alkylcyclohexyl, cyclohexylcyclohexyl and phenylcyclohexyl radicals.

2. 4-cyclohexylcyclohexyl ester of 2-cyclohexene-l-caproic acid.

3. 2-cyclohexylcyclohexyl ester of Z-cyclohexene-l-caproic acid.

4. 4-phenylcyclohexyl ester of 2-cyclohexene- I-caproic acid.

GERALD H. COLEMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,352,746 Wasum July 4, 1944 2,396,013 Jones et al Mar. 5, 1946 2,441,183 Bludworth et a1. May 11, 1948 

